Let's play! Remember just to put a money which you will not need and you'll not take care about it.

In which 'expensive' crytocurrencies I would invest?

Ethereum
This is the clear bet. This coin is growing and growing and it will be probably like Bitcoin.

Monero
This is a special coin, it's used in special markets because you can not track those transactions. It's famous because of that, but it didn't stop of growing and developers are creating things like web mining. Then, it's a good bet from my point of view.

Litecoin
Another coin which will grow. Same told for Ethereum will apply here.

In which 'cheap' crytocurrencies I would invest?

The important point is: Do you want to win money? Or do you want to be rich?

Like IOTA but so much newer and because of that, so much cheaper than IOTA. Then you can get so much tokens for same price.

About all these, IOTA & Streamr could have more future. Why? Because they are focused on the IoT and they could be the next revolution. Imagine, you are going in a car and the car itself will pay the toll with these currencies. Or you need milk in your smart fridge and the fridge itself will pay a delivery to Amazon.

In which crytocurrencies I would not invest at ling time and why?

Bitcoin
It has issues about currently number of transactions. Anyway, it's the coin by excellence.
I would not recommend it, because it's so so expensive.

Ripple
Ripple was created by a few 'real' banks. Probably in the future, other banks will create other coins and nobody will use all of them. It's growing, but invest on it for a short time.

How to buy?

It's not so easy to buy crytocurrencies in your 1st try. An easy way could be:

Is Ubucon made for me?

This event is just for you! ;) You don't need to be a developer, because you'll enjoy a lot of talks about everything you can to imagine about Ubuntu and share great moments with other users.
Even the language won't be a problem. there, you'll meet people from everywhere and surely someone will speak in your language :)